python获取日期加减之后的日期
python语言中的datetime模块可以利用其中的方法获取不同的日期，比如获取当前日期、明天、昨天、上个月、下个月和明年。下面利用几个实例说明这些日期的获取方法，操作如下：
第一步，利用datetime模块获取当前日期 datetime.date.today(); 如下图所示：
第二步，获取当前日期前一天日期，利用当前日期减去一天，如下图所示：
第三步，获取当前日期后一天日期，利用当前日期加上一天，如下图所示：
第四步，获取当前日期下一个月日期，利用当前日期加上30天，如下图所示：
第五步，获取当前日期上一个月的日期，利用当前日期减去30天，如下图所示：
第六步，获取当前日期返回明年今天的日期，利用当前日期加上365天，如下图所示：
- python获取前后N天或前后N个月的日期
# -*- coding: utf-8 -*-
#-----------------------------------------------------------------------------------
import datetime
#获取366天前的日期
day=(datetime.date.today() - datetime.timedelta(days=366)).strftime('%Y-%m-%d')
print(day)
#获取366天后的日期
day=(datetime.date.today() + datetime.timedelta(days=366)).strftime('%Y-%m-%d')
print(day)
#3周前期
day=(datetime.date.today() + datetime.timedelta(weeks=-3)).strftime('%Y-%m-%d')
print(day)
#-----------------------------------------------------------------------------------
'''获取当前日期前后N天或N月的日期'''
from time import strftime, localtime
from datetime import timedelta, date
import calendar
year = strftime("%Y", localtime())
mon = strftime("%m", localtime())
day = strftime("%d", localtime())
hour = strftime("%H", localtime())
min = strftime("%M", localtime())
sec = strftime("%S", localtime())
def today():
'''''
get today,date format="YYYY-MM-DD"
'''''
return date.today()
def todaystr():
get date string, date format="YYYYMMDD"
return year + mon + day
def datetime():
'''''
get datetime,format="YYYY-MM-DD HH:MM:SS"
return strftime("%Y-%m-%d %H:%M:%S", localtime())
def datetimestr():
'''''
get datetime string
date format="YYYYMMDDHHMMSS"
return year + mon + day + hour + min + sec
def get_day_of_day(n=0):
'''''
if n>=0,date is larger than today
if n<0,date is less than today
date format = "YYYY-MM-DD"
if (n < 0):
n = abs(n)
return date.today() - timedelta(days=n)
else:
return date.today() + timedelta(days=n)
def get_days_of_month(year, mon):
'''''
get days of month
return calendar.monthrange(year, mon)[1]
def get_firstday_of_month(year, mon):
'''''
get the first day of month
date format = "YYYY-MM-DD"
days = "01"
if (int(mon) < 10):
mon = "0" + str(int(mon))
arr = (year, mon, days)
return "-".join("%s" % i for i in arr)
def get_lastday_of_month(year, mon):
'''''
get the last day of month
date format = "YYYY-MM-DD"
days = calendar.monthrange(year, mon)[1]
mon = addzero(mon)
arr = (year, mon, days)
return "-".join("%s" % i for i in arr)
def get_firstday_month(n=0):
'''''
get the first day of month from today
n is how many months
(y, m, d) = getyearandmonth(n)
d = "01"
arr = (y, m, d)
return "-".join("%s" % i for i in arr)
def get_lastday_month(n=0):
'''''
get the last day of month from today
n is how many months
return "-".join("%s" % i for i in getyearandmonth(n))
def getyearandmonth(n=0):
'''''
get the year,month,days from today
befor or after n months
thisyear = int(year)
thismon = int(mon)
totalmon = thismon + n
if (n >= 0):
if (totalmon <= 12):
days = str(get_days_of_month(thisyear, totalmon))
totalmon = addzero(totalmon)
return (year, totalmon, days)
else:
i = totalmon / 12
j = totalmon % 12
if (j == 0):
i -= 1
j = 12
thisyear += i
days = str(get_days_of_month(thisyear, j))
j = addzero(j)
return (str(thisyear), str(j), days)
else:
if ((totalmon > 0) and (totalmon < 12)):
days = str(get_days_of_month(thisyear, totalmon))
totalmon = addzero(totalmon)
return (year, totalmon, days)
else:
i = totalmon / 12
j = totalmon % 12
if (j == 0):
i -= 1
j = 12
thisyear += i
days = str(get_days_of_month(thisyear, j))
j = addzero(j)
return (str(thisyear), str(j), days)
def addzero(n):
'''''
add 0 before 0-9
return 01-09
nabs = abs(int(n))
if (nabs < 10):
return "0" + str(nabs)
else:
return nabs
def get_today_month(n=0):
'''''
获取当前日期前后N月的日期
if n>0, 获取当前日期前N月的日期
if n<0, 获取当前日期后N月的日期
date format = "YYYY-MM-DD"
(y, m, d) = getyearandmonth(n)
arr = (y, m, d)
if (int(day) < int(d)):
arr = (y, m, day)
return "-".join("%s" % i for i in arr)
if __name__ == "__main__":
print today()#获取当前日期，2017-12-02
print todaystr()#20171202
print datetime()#2017-12-02 16:37:19